Abstract: The invention provides an implantable intracranial device for the site-specific delivery of a pharmaceutically active agent to a human or animal for treating a mental or neurological disorder, such as Alzheimer's disease, schizophrenia or other psychoses. The biodegradable device includes a pharmaceutically active agent for treating the disorder, polymeric nano-lipoparticles into or onto which the pharmaceutically active agent is embedded; and a polymeric matrix or scaffold incorporating the nano-lipoparticles. The nano-lipoparticles can be in the form of nano-liposhells or nano-lipobubbles. The nano-liposhells or nano-lipobubbles can include an essential fatty acid or can be conjugated to a peptide ligand which targets the device to a specific cell into which the therapeutic agent can be delivered. The device can be implanted in the sub-arachnoid space in the region of the frontal lobe of the brain.